12 second junkyard 318
Alot depends on cam and compresion. And alot is on the cam. To low on the compresion and it will effect everything from idle to WOT power. Most performance cams are ground on a 110 for that muscle car sound and chop your used to hearing. By going up to a 112 it will smooth out a little bit. At 114, it will be very smooth.
Going the otherway, down to a 108, it will have a nasty chop to it. At 106, it will be reallllly ruff.
Run as much compresion as you can for best results, period. Of course a 12-1 ratio and a RV cam will not mix so well and probably require race fuel, but I think you get the picture. The key word of the day is balance.